MANILA, Philippines - President Barack Obama is heading home after a four-country swing through Asia.

He is still confronting the challenge of how to deal with Russia's threatening moves toward Ukraine. The issue clouded an Obama tour that was meant to reassure anxious allies in the orbit of a rising China that the U.S. will always defend them.

Before getting on Air Force One for the flight Tuesday to Washington, Obama rallied U.S. and Philippine troops at Fort Bonifacio, just outside Manila.

He also placed a wreath at the American cemetery there. The White House says the burial ground holds the largest number of U.S. war dead from World War II, more than 17,200 graves.